3.0T magnetic resonance imaging-based hip bone models for femoroacetabular impingement syndrome are equivalent to computed tomography-based models.

This study aimed to compare three-dimensional (3D) proximal femoral and acetabular surface models generated from 3.0T magnetic resonance imaging (MRI) to the clinical gold standard of computed tomography (CT). Ten intact fresh-frozen cadaveric hips underwent CT and 3.0T MRI scans. The CT- and MRI-based segmented models were superimposed using a validated 3D-3D registration volume-merge method to compare them. The least surface-to-surface distance between the models was calculated by a point-to-surface calculation algorithm using a custom-written program. The variables of interest were the signed and absolute surface-to-surface distance between the paired bone models. One-sample t-tests were performed using a signed and absolute test value of 0.16 mm and 0.37 mm, respectively, based on a previous study that validated 1.5T MRI bone models by comparison with CT bone models. For the femur, the average signed and absolute surface-to-surface distance was 0.18 ± 0.09 mm and 0.30 ± 0.06 mm, respectively. There was no difference in the signed surface-to-surface distance and the 0.16 mm test value (t = 0.650, p = 0.532). However, the absolute surface-to-surface difference was less than the 0.37 mm test value (t = -4.025, p = 0.003). For the acetabulum, the average signed and absolute surface-to-surface distance was -0.06 ± 0.06 mm and 0.26 ± 0.04 mm, respectively. The signed (t = -12.569, p < 0.001) and absolute (t = -8.688, p < 0.001) surface-to-surface difference were less than the 0.16 mm and 0.37 mm test values, respectively. Our data shows that 3.0T MRI bone models are more similar to CT bone models than previously validated 1.5T MRI bone models. This is likely due to the higher resolution of the 3T data.

Highly Porous Acetabular Cup and Augment Constructs in Complex Revision Total Hip Arthroplasty: What Predicts 10-Year Implant Survivorship?

BACKGROUND: Porous tantalum acetabular cup and augment constructs have demonstrated favorable outcomes up to 5 years postsurgery despite severe bone loss during revision total hip arthroplasty (THA). Prior literature lacks long-term studies with substantial case numbers. This study aims to assess long-term clinical and radiographic outcomes 10 years postsurgery in patients undergoing revision THA with porous tantalum acetabular cup-augment constructs and determine factors associated with long-term survivorship. METHODS: Between 2000 and 2012, 157 revision THAs were performed in cases with major acetabular defects (mainly Paprosky type IIIA and IIIB) utilizing porous tantalum cup-augment constructs. Pelvic discontinuity was noted intraoperatively in 17 hips (11%). Postoperative radiographs were evaluated at regular intervals for implant stability and radiolucent lines. There were 49 patients who had complete radiographic follow-up at 10 years or longer postsurgery. RESULTS: The 10-year survivorship free of revision of the cup-augment construct for aseptic loosening was 93%, free of any acetabular construct revision was 91%, free of any hip rerevision was 77%, and free of any reoperation was 75%. Pelvic discontinuity was associated with increased risk of reoperation (hazard ratio [HR] = 2.8), any hip rerevision (HR = 3.2), any cup-augment construct revision (HR = 11.8), and aseptic construct revision (HR = 10.0). Of unrevised cases with radiographs at 10 years, 4 hips showed radiographic loosening. Mean Harris hip scores improved from 47 preoperatively to 79 at 10 years. CONCLUSIONS: Porous tantalum acetabular cup-augment constructs used in revision THA with severe acetabular bone loss provide excellent implant survivorship at 10 years when the acetabulum is intact. Due to lower survivorship of cup-augment constructs in cases of pelvic discontinuity, additional construct fixation or stabilization methods are recommended, when a discontinuity is present. LEVEL OF EVIDENCE: IV.

Hip and Pelvis Movement Patterns in Patients With Femoroacetabular Impingement Syndrome Differ From Controls and Change After Hip Arthroscopy During a Step-Down Pivot-Turn Task.

Background: Alterations in hip kinematics during functional tasks occur in positions that cause anterior impingement in patients with femoroacetabular impingement (FAI) syndrome. However, tasks that do not promote motions of symptomatic hip impingement remain understudied. Purpose: To compare movement patterns of the hip and pelvis during a step-down pivot-turn task between patients with FAI and controls as well as in patients with FAI before and after hip arthroscopy. Study Design: Controlled laboratory study. Methods: Three-dimensional motion capture was acquired in 32 patients with FAI and 27 controls during a step-down pivot-turn task. An FAI subsample (n = 14) completed testing 9.2 ± 2.0 months (mean ± SD; range, 5.8-13.1 months) after hip arthroscopy. Statistical parametric mapping analysis was used to analyze hip and pelvis time series waveforms (1) between the FAI and control groups, (2) in the FAI group before versus after hip arthroscopy, and (3) in the FAI group after hip arthroscopy versus the control group. Continuous parametric variables were analyzed by paired t test and nonparametric variables by chi-square test. Results: There were no significant differences in demographics between the FAI and control groups. Before hip arthroscopy, patients with FAI demonstrated reduced hip flexion (P = .041) and external rotation (P = .027), as well as decreased anterior pelvic tilt (P = .049) and forward rotation (P = .043), when compared with controls. After hip arthroscopy, patients demonstrated greater hip flexion (P < .001) and external rotation of the operative hip (P < .001), in addition to increased anterior pelvic tilt (P≤ .036) and pelvic rise (P≤ .049), as compared with preoperative values. Postoperatively, the FAI group demonstrated greater hip flexion (P≤ .047) and lower forward pelvic rotation (P = .003) as compared with the control group. Conclusion: Movement pattern differences between the FAI and control groups during the nonimpingement-related step-down pivot-turn task were characterized by differences in the sagittal and transverse planes of the hip and pelvis. After hip arthroscopy, patients exhibited greater hip flexion and external rotation and increased pelvic anterior tilt and pelvic rise as compared with presurgery. When compared with controls, patients with FAI demonstrated greater hip flexion and lower pelvic forward rotation postoperatively. Clinical Relevance: These findings indicate that hip and pelvis biomechanics are altered even during tasks that do not reproduce the anterior impingement position.

Effect of Differing Orientation and Magnitude of Femoral Torsion on Outcomes and Achievement of the MCID and PASS at 5 Years After Hip Arthroscopy for Femoroacetabular Impingement Syndrome.

BACKGROUND: Femoral torsion measurements and outcomes are variable throughout the literature and have focused on short-term follow-up. However, there is a paucity of literature investigating clinically meaningful outcomes at midterm follow-up after hip arthroscopy for femoroacetabular impingement syndrome (FAIS). PURPOSE: To quantify femoral version using computed tomography imaging in patients with FAIS and to explore the relationship between version abnormalities and 5-year outcomes after hip arthroscopy. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: Patients who underwent primary hip arthroscopy for FAIS between January 2012 and November 2017 were identified. Patients were included if they had 5-year follow-up with completion of ≥1 patient-reported outcome (PRO) scores and excluded if they had Tönnis grade >1, revision hip surgery, a concomitant hip procedure, a developmental disorder, or a lateral center-edge angle <20°. Torsion groups were defined as severe retrotorsion (<0°), moderate retrotorsion (0.1°-5°), normal torsion (5.1°-20°), moderate antetorsion (20.1°-25°), and severe antetorsion (>25.1°) based on computed tomography measurements. Patient characteristics were analyzed among the torsion cohorts, as were preoperative and 5-year PROs: Hip Outcome Score-Activities of Daily Living, Hip Outcome Score-Sports Subscale, modified Harris Hip Score, international Hip Outcome Tool, visual analog scale for pain, and visual analog scale for satisfaction. Achievement rates of cohort-specific thresholds for the minimal clinically important difference and Patient Acceptable Symptom State were calculated and compared among cohorts. RESULTS: A total of 362 patients (244 female, 118 male; mean ± SD age, 33.1 ± 11.5 years; body mass index, 26.9 ± 17.8) met inclusion/exclusion criteria and were analyzed at a final mean follow-up of 64.3 ± 9.4 months (range, 53.5-115.5 months). Mean femoral torsion was 12.8°± 9.2°. The number of patients within each group was 20 for severe retrotorsion (torsion, -6.3°± 4.9°), 45 for moderate retrotorsion (2.7°± 1.3°), 219 for normal torsion (12.2°± 4.1°), 39 for moderate antetorsion (21.9°± 1.3°), and 39 for severe antetorsion (29.0°± 4.2°). No significant differences in age, body mass index, sex, smoking status, workers' compensation, psychiatric history, back pain, or physical activity were found among the torsional groups. All groups demonstrated significant improvements at 5 years postoperatively (P < .01 for all). All torsion subgroups demonstrated similar pre- to postoperative changes in PROs (P≥ .515) and PRO values at 5-year follow-up (P≥ .098). There were no significant differences in the achievement of the minimal clinically important difference (P≥ .422) or Patient Acceptable Symptom State (P≥ .161) for any of the PROs among the torsion groups. CONCLUSION: The orientation and severity of femoral torsion at the time of hip arthroscopy for FAIS in this study's cohort did not affect the propensity for clinically meaningful outcome improvement at midterm follow-up.

Ultrasound Demonstrates Potential in Identifying Proximal Femoral Morphology Before and After Cam Resection: A Cadaveric Study.

PURPOSE: (1) To compare alpha angles measured on fluoroscopy with those measured on ultrasound pre- and postosteoplasty and (2) to determine whether ultrasound can adequately assess cam deformity correction. METHODS: Twelve full-body specimens (20 hips) were analyzed. Images using fluoroscopy and ultrasound were captured of the operative hip with the hip in 6 consistent positions: 3 views in hip extension (neutral [N], 30° internal rotation [IR], and 30° external rotation [ER]) and 3 views in hip flexion of 50° (neutral [F-N], 40° external rotation [F-ER40], and 60° external rotation [F-ER60]). A curved-array ultrasound transducer probe was used with the transducer placed in line with the femoral neck to evaluate the proximal femoral morphology. An open femoral osteoplasty using an anterior approach was performed. Fluoroscopy and ultrasound were again used to capture images with the hip in the same 6 positions. Bland-Altman plots were used to determine whether fluoroscopic and ultrasound alpha angles agreed at each position. Independent t-tests were used to compare the alpha angles between the 2 modalities at each position, and paired t-tests were used to compare preoperative and postoperative alpha angles at each position. RESULTS: No significant differences between the alpha angle on fluoroscopy and ultrasound at all 6 positions were appreciated preosteoplasty. The mean preoperative alpha angle on ultrasound in each position was as follows: N (55.4° ± 5.9° vs 43.0° ± 2.1°), IR (55.1° ± 5.3° vs 43.9° ± 5.5°), ER (58.6° ± 5.6° vs 42.8° ± 3.0°), F-N (53.9° ± 5.5° vs 41.6° ± 3.3°), F-ER40 (55.5° ± 4.6° vs 41.5° ± 2.7°), and F-ER60 (57.9° ± 6.5° vs 41.2° ± 4.2°). The mean preoperative and postoperative alpha angle on fluoroscopy in each position were as follows: N (56.0 ± 12.8° vs 43.1 ± 2.1°), IR (54.1 ± 13.4° vs 41.9 ± 2.9°), ER (61.2 ± 11.0° vs 44.2 ± 1.9°), F-N (57.9 ± 10.6° vs 44.0 ± 2.3°), F-ER40 (59 ± 8.2° vs 42 ± 2.2°), and F-ER60 (55 ± 7.6° vs 41.1 ± 2.6°). Postosteoplasty, there was no significant difference between the mean alpha angle on fluoroscopy versus ultrasound in any position except F-N (44.0 ± 2.3 vs 41.6 ± 3.3, P = .015). Bland-Altman plots showed a high level of agreement between alpha angle values on fluoroscopy and ultrasound at all positions pre- and postosteoplasty. There was a significant reduction in alpha angle measured on ultrasound and fluoroscopy at each position following osteoplasty. There were no significant differences in the delta of the pre- and postosteoplasty alpha angle measurements between fluoroscopy and ultrasound. CONCLUSIONS: Ultrasound is a useful tool for assessing a cam deformity in patients with femoroacetabular impingement syndrome and for determining adequate resection of a cam deformity intraoperatively. CLINICAL RELEVANCE: Due to the inherent limitations and risks of the fluoroscopy, it is worth evaluating other nonionizing imaging modalities. Ultrasound has potential to be an accessible, cost-effective, and safe imaging modality that lacks radiation and is commonly used for intra-articular hip injections and dynamic examination of the hip.

Isolated, Full-Thickness Proximal Rectus Femoris Injury in Competitive Athletes: A Systematic Review of Injury Characteristics and Return to Play.

Background: Characteristics regarding mechanism of injury, management, and return-to-play (RTP) rate and timing are important when treating and counseling athletes with rectus femoris tears. Purpose: To systematically review the literature to better understand the prevalence, sporting activity, injury mechanisms, and treatment of patients with rectus femoris injury and to provide prognostic information regarding the rate and timing of RTP. Study Design: Systematic review; Level of evidence, 4. Methods: Following the 2020 PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, we queried PubMed/MEDLINE, Cochrane, OVID, EMBASE, and Google Scholar in March 2022 for studies reporting on athletes sustaining isolated, full-thickness tearing, or bony avulsion injuries to the proximal rectus femoris during sporting activity. Excluded were studies without evidence of full-thickness tearing or avulsion, with athletes sustaining concomitant injuries, or with injuries occurring from nonsporting activities. The percentage of athletes sustaining injuries was calculated based on sport, injury mechanism, and management (nonoperative versus operative). Results: Of 132 studies initially identified, 18 were included, comprising 132 athletes (mean age, 24.0 ± 5.4 years; range, 12-43 years). The most common sporting activities were soccer (70.5%) and rugby (15.2%). The most reported mechanisms of injury were kicking (47.6%) and excessive knee flexion/forced hip extension (42.9%). Avulsion injuries were reported in 86% (n = 114) of athletes. Nonoperative management was reported in 19.7% of athletes, with operative management performed in 80.3%. The mean follow-up time was 21.4 ± 11.4 months (range, 1.5-48 months). The RTP rate was 93.3% (n = 14) in nonoperatively treated and 100% (n = 106) in operatively treated athletes, and the mean RTP time was 11.7 weeks (range, 5.5-15.2 weeks) in nonoperatively treated and 22.1 weeks (range, 14.0-37.6 weeks) in operatively treated athletes. Complications were reported in 7.7% (2/26) of nonoperatively treated and 18% (n = 19/106) of operatively treated athletes. Conclusion: Full-thickness proximal rectus femoris injuries occurred most frequently in athletes participating in soccer and rugby secondary to explosive, eccentric contractions involved in kicking and sprinting. Operative management was performed in the majority of cases. Athletes who underwent operative repair had a 100% RTP rate versus 93.3% in athletes treated nonoperatively.

Noninvasive shape-fitting method quantifies cam morphology in femoroacetabular impingement syndrome: Implications for diagnosis and surgical planning.

There are considerable limitations associated with the standard 2D imaging currently used for the diagnosis and surgical planning of cam-type femoroacetabular impingement syndrome (FAIS). The aim of this study was to determine the accuracy of a new patient-specific shape-fitting method that quantifies cam morphology in 3D based solely on preoperative MRI imaging. Preoperative and postoperative 1.5T MRI scans were performed on n = 15 patients to generate 3D models of the proximal femur, in turn used to create the actual and the virtual cam. The actual cams were reconstructed by subtracting the postoperative from the preoperative 3D model and used as reference, while the virtual cams were generated by subtracting the preoperative 3D model from the virtual shape template produced with the shape-fitting method based solely on preoperative MRI scans. The accuracy of the shape-fitting method was tested on all patients by evaluating the agreement between the metrics of height, surface area, and volume that quantified virtual and actual cams. Accuracy of the shape-fitting method was demonstrated obtaining a 97.8% average level of agreement between these metrics. In conclusion, the shape-fitting technique is a noninvasive and patient-specific tool for the quantification and localization of cam morphology. Future studies will include the implementation of the technique within a clinically based software for diagnosis and surgical planning for cam-type FAIS.

Defining the Minimal Clinically Important Difference and Patient Acceptable Symptom State After Endoscopic Gluteus Medius or Minimus Repair With or Without Labral Treatment and Routine Capsular Closure at Minimum 5-Year Follow-up.

BACKGROUND: There is a paucity of information in the literature on midterm outcomes of endoscopic gluteus medius and/or minimus repair with concomitant labral treatment using only modern surgical techniques. PURPOSE: To define the minimal clinically important difference (MCID) and Patient Acceptable Symptom State (PASS) at a minimum of 5 years postoperatively for patients undergoing endoscopic hip abductor repair with routine capsular closure. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: Consecutive patients who underwent primary endoscopic repair of gluteus medius and/or minimus tears between January 2012 and December 2015 by the senior author were eligible for inclusion. Patient-reported outcome scores were assessed preoperatively and at 5 years postoperatively: Hip Outcome Score-Activities of Daily Living (HOS-ADL), HOS-Sport Specific (HOS-SS), modified Harris Hip Score (mHHS), 12-item International Hip Outcome Tool (iHOT-12), and visual analog scale (VAS) for pain. The MCID was uniquely calculated using the distribution method, and the PASS was determined via the anchor-based method utilizing receiver operating characteristic curves and Youden index. RESULTS: A total of 46 patients were included in the study. The majority were female (87.0%), with a mean ± standard deviation age of 59.1 ± 8.9 years and body mass index of 27.3 ± 6.9. Significant postoperative improvements (P < .001) in each of the 5 patient-reported outcomes were observed at 5 years postoperatively. The MCID threshold values were calculated as follows: HOS-ADL, 11.5; HOS-SS, 15.1; mHHS, 13.3; iHOT-12, 11.8; and VAS, 15.8. The PASS thresholds were calculated as follows: HOS-ADL, 75.7; HOS-SS, 79.7; mHHS, 81.2; and iHOT-12, 60.8. A majority of patients achieved a clinically significant outcome, with 96.2% of patients reaching a threshold score for the MCID or PASS for at least 1 patient-reported outcome. CONCLUSION: Endoscopic hip abductor repair with concomitant arthroscopic labral treatment has a high rate of achievement of clinically significant outcomes and survivorship at a minimum 5-year follow-up. We defined the MCID for the HOS-ADL, HOS-SS, mHHS, iHOT-12, and VAS outcome scores to be 11.5, 15.1, 13.3, 11.8, and 15.8, respectively. The PASS threshold scores for the HOS-ADL, HOS-SS, mHHS and iHOT-12 scores of 75.7, 79.7, 81.2, and 60.8, respectively. Future researchers and clinicians can use the MCID and PASS values established in this study to better evaluate mid-term outcomes of patients undergoing hip abductor repair.

Hip Arthroscopy for the Treatment of Femoroacetabular Impingement Syndrome in Hips With Mild Osteoarthritis (Tönnis Grade 1): A Matched Comparative Cohort Analysis at Minimum 5-Year Follow-up.

BACKGROUND: There is a paucity of information in the literature on midterm outcomes from the arthroscopic treatment of femoroacetabular impingement syndrome (FAIS) with concomitant labral treatment in patients with mild osteoarthritis (OA) using modern surgical techniques. PURPOSE: To compare outcomes of hip arthroscopy for the treatment of FAIS between patients with mild OA (Tönnis grade 1) and patients without OA (Tönnis grade 0) at minimum 5-year follow-up. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: Patients were identified who underwent primary hip arthroscopy for FAIS with routine capsular closure between January 2012 and December 2015. Patients with Tönnis grade 1 were matched 1:3 by age, sex, and body mass index to patients without OA. The Hip Outcome Score-Activities of Daily Living (HOS-ADL), HOS-Sports Subscale (HOS-SS), modified Harris Hip Score, and 12-item International Hip Outcome Tool were collected preoperatively and at 5 years postoperatively and compared between groups using an independent t test. Survivorship rate and percentage achievement of a Patient Acceptable Symptom State (PASS) or minimal clinically important difference (MCID) were compared using a Fisher exact test. RESULTS: A total of 50 patients (54 hips) with Tönnis grade 1 were matched to 162 patients (162 hips) with Tönnis grade 0. The mean ± SD age and body mass index of the Tönnis grade 1 group were 44.5 ± 9.6 years and 28.5 ± 5.5, respectively. Patient-reported outcome (PRO) scores improved significantly for both groups from presurgery to 5 years postoperatively for all PROs (P≤ .03). There were no significant differences in preoperative PROs between the groups. Patients with Tönnis grade 1 had significantly lower postoperative scores on the HOS-ADL (74.7 ± 22.6 vs 83.0 ± 20.1; P = .04) and HOS-SS (58.8 ± 33.7 vs 71.8 ± 29.3; P = .03) than patients with grade 0. Patients with Tönnis grade 1 also had significantly lower rates of achievement of the MCID (57.1% vs 80.2%; P < .01) and PASS (34.1% vs 53.4%; P = .03) for any PRO when compared with patients with Tönnis grade 0. Gross survivorship was significantly lower for Tönnis grade 1 versus grade 0 (77.8% vs 96.9%; P < .001). CONCLUSION: Patients with Tönnis grade 1 arthritis experienced significant improvement in PROs after hip arthroscopy for the treatment of FAIS. However, they had significantly lower postoperative HOS-ADL and HOS-SS scores with significantly lower rates of achievement on the MCID and PASS, with a significantly lower gross survivorship rate at a minimum 5 years postoperatively in comparison with those with Tönnis grade 0 changes.

Ultrasound Can Determine Joint Distraction During Hip Arthroscopy but Fluoroscopic-Guided Portal Placement Is Superior.

Purpose: To compare joint distraction measured on ultrasound (US) with joint space width (JSW) measured on fluoroscopy in hip arthroscopy and to determine whether ultrasound guidance is as safe and effective as fluoroscopy, the current gold standard, for establishing arthroscopic portals. Methods: Cadaveric whole-body specimens were positioned supine and subjected to 60 lbs. of unilateral axial traction using a distal femoral Steinman pin. Joint distraction was measured via JSW on fluoroscopic and ultrasound images. A single, fellowship-trained orthopaedic surgeon established anterolateral arthroscopy portals via ultrasound or fluoroscopic guidance in a randomized sequence. Total procedure time, number of times the spinal needle pierced the capsule, and iatrogenic chondral or labral injury were recorded. Results: Twelve full-body specimens (20 hips) underwent distraction, and 17 hips underwent portal placement with fluoroscopic (n = 8) or ultrasound (n = 9) guidance. JSW measured on ultrasound was significantly less laterally (13.0 vs 9.2 mm, P < .001), apically (16.7 vs 9.2 mm, P < .001), and medially (17.9 vs 9.2 mm, P < .001). Successful portal entry was achieved in every specimen. Average procedure time was 133 ± 51 seconds for the fluoroscopy group and 371 ± 260 seconds for the ultrasound group (P = .026). Fluoroscopic guidance required significantly less needle insertion attempts at 1.13 compared with 3.33 attempts for ultrasound (P = .022). Labral damage was greater in the ultrasound group at 66.67% compared with 12.50% for fluoroscopy (P = .0497). Conclusions: Joint distraction measured on ultrasound can be used to subjectively determine if the joint is adequately distracted in hip arthroscopy. Ultrasound-guided portal placement was associated with more needle insertion attempts, iatrogenic injury of the labrum, and overall procedure time in comparison to fluoroscopic guidance. Clinical Relevance: Fluoroscopy is the gold standard to confirm adequate joint distraction, aid in establishing arthroscopy portals, and evaluate resection of the femoral head during hip arthroscopy but exposes the patient to ionizing radiation, requires additional operators in the operating room, and involves the need for a heavy lead shield. Alternatives to fluoroscopy are needed, but ultrasound has not proven superior in our cadaveric model.

Three-Dimensional Quantification of Cam Resection Using MRI Bone Models: A Comparison of 2 Techniques.

Background: The current clinical standard for the evaluation of cam deformity in femoroacetabular impingement syndrome is based on radiographic measurements, which limit the ability to quantify the complex 3-dimensional (3D) morphology of the proximal femur. Purpose: To compare magnetic resonance imaging (MRI)-based metrics for the quantification of cam resection as derived using a best-fit sphere alpha angle (BFS-AA) method and using 3D preoperative-postoperative surface model subtraction (PP-SMS). Study Design: Descriptive laboratory study. Methods: Seven cadaveric hemipelvises underwent 1.5-T MRI before and after arthroscopic femoral osteochondroplasty, and 3D bone models of the proximal femur were reconstructed from the MRI scans. The alpha angles were measured radially along clockfaces using a BFS-AA method from the literature and plotted as continuous curves for the pre- and postoperative models. The difference between the areas under the curve for the pre- and postoperative models was then introduced in the current study as the BFS-AA-based metric to quantify the cam resection. The cam resection was also quantified using a 3D PP-SMS method, previously described in the literature using the metrics of surface area (FSA), volume (FV), and height (maximum [FHmax] and mean [FHmean]). Bivariate correlation analyses were performed to compare the metrics quantifying the cam resection as derived from the BFS-AA and PP-SMS methods. Results: The mean ± standard deviation maximum pre- and postoperative alpha angle measurements were 59.73° ± 15.38° and 48.02° ± 13.14°, respectively. The mean for each metric quantifying the cam resection with the PP-SMS method was as follows: FSA, 540.9 ± 150.7 mm2; FV, 1019.2 ± 486.2 mm3; FHmax , 3.6 ± 1.0 mm; and FHmean, 1.8 ± 0.5 mm. Bivariate correlations between the BFS-AA-based and PP-SMS-based metrics were strong: FSA (r = 0.817, P = .012), FV (r = 0.888, P = .004), FHmax (r = 0.786, P = .018), and FHmean (r = 0.679, P = .047). Conclusion: Strong positive correlations were appreciated between the BFS-AA and PP-SMS methods quantifying the cam resection. Clinical Relevance: The utility of the BFS-AA technique is primarily during preoperative planning. The utility of the PP-SMS technique is in the postoperative setting when evaluating the adequacy of resection or in patients with persistent hip pain with suspected residual impingement. In combination, the techniques allow surgeons to develop a planned resection while providing a means to evaluate the depth of resection postoperatively.

Outcomes for the Arthroscopic Treatment of Femoroacetabular Impingement Syndrome With Acetabular Retroversion: A 3D Computed Tomography Analysis.

BACKGROUND: Increased attention has been directed toward the acetabular morphology in the management of patients with femoroacetabular impingement syndrome (FAIS). Whether acetabular version influences patient-reported outcomes remains poorly understood. PURPOSE: To use computed tomography (CT)-based 3-dimensional (3D) bone models to (1) quantify acetabular version in patients with FAIS, (2) compare acetabular version on 3D bone models with current plain radiographic parameters, and (3) explore the relationship between the magnitude of acetabular version and minimum 2-year clinical outcomes after hip arthroscopy. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: Three-dimensional models of the pelvis and femur were generated by semiautomated segmentation and aligned to a standard coordinate system. Acetabular version was quantified at the 3-o'clock position, and 3 groups were identified: acetabular retroversion (AR; <15°), normal acetabular version (NV; 15°-25°), and acetabular anteversion (AA; >25°). Patient demographic characteristics, plain radiographic parameters, and clinical outcomes were analyzed, including the Hip Outcome Score-Activities of Daily Living, Hip Outcome Score-Sports Subscale, modified Harris Hip Score (mHHS), International Hip Outcome Tool (iHOT-12), and visual analog scale (VAS) for pain and satisfaction. RESULTS: Preoperative CT scans were acquired in 105 consecutive patients before hip arthroscopy for FAIS, of which 84 (80.0%) completed minimum 2-year patient-reported outcomes. The mean ± SD age and body mass index of patients were 33.9 ± 12.6 years and 26.0 ± 5.4, respectively; 70.2% were female. The number of patients and the mean central acetabular version within each group were as follows: AR (n = 12; 11.3°± 2.7°), NV (n = 56; 20.7°± 2.9°), and AA (n = 16; 28.5°± 2.7°). Posterior wall sign was the only plain radiographic parameter that was significantly more observed in the AR group than in the other 2 groups. At minimum 2-year follow-up, significant between-group differences in the mHHS, iHOT-12, and VAS for pain and satisfaction (P < .05) were appreciated, while post hoc analysis with Bonferroni correction (P < .0167) found lower scores on the mHHS, iHOT-12, and VAS for pain and satisfaction in patients with AR as compared with NV. Lower scores on the VAS for satisfaction were reported in patients with AR when compared with AA (P = .006) but not on the mHHS (P = .023), iHOT-12 (P = .032), or VAS for pain (P = .072). CONCLUSION: Traditional plain radiographic indices to describe AR, including crossover sign and ischial spine sign, were not reliable in defining AR according to 3D models derived from CT scans. Only the posterior wall sign was observed in a higher proportion in the AR group. Patients with AR demonstrated inferior outcomes when compared with patients with NV and AA after hip arthroscopy for FAIS.

Determining the Roles of the Anterior Cruciate Ligament, Posterolateral Corner, and Medial Collateral Ligament in Knee Hyperextension Using the Heel-Height Test.

Background: Anterior cruciate ligament (ACL) tears are often associated with other ligamentous injuries. The side-to-side difference in heel height can represent a valuable diagnostic tool in the setting of multiligamentous injuries. Purpose: To assess in a cadaveric model how sequential sectioning of the static stabilizing structures of the knee (ACL, fibular collateral ligament [FCL], popliteus tendon [PLT], popliteofibular ligament [PFL], and medial collateral ligament [MCL]) influences heel-height measurements when comparing groups undergoing initial transection of the ACL versus FCL and to assess posterior tibial slope after sequential sectioning. Study Design: Controlled laboratory study. Methods: A total of 16 fresh cadaveric knees were carefully dissected to expose the ACL, FCL, PLT, PFL, and MCL. Each knee was randomized to either the ACL-first or FCL-first group based on the initial structure sectioned. The sectioning order was as follows: (1) ACL or FCL, (2) FCL or ACL, (3) PLT, (4) PFL, and (5) MCL. Heel height was measured with a standardized superiorly directed 12-N·m force applied to the knee while stabilizing the femur; heel height was also measured with a clinician-applied force. The measurements were compared between and within groups for each sectioned state. The correlation between tibial slope and heel-height measurements was analyzed. Results: There were no significant differences in heel-height measurements between the ACL-first and FCL-first groups (P = .863). Combined ACL-FCL injuries led to a 2.85 ± 0.83-cm increase in heel height compared to the intact state. Significant increases in heel height occurred after all sectioned states, except the PFL sectioned state. Combined ACL-posterolateral corner (PLC) injuries resulted in a 3.72 ± 1.02-cm increase in heel height, and additional sectioning of the MCL resulted in a 4.73 ± 1.35-cm increase compared to the intact state. Tibial slope was not correlated with increases in heel height after each sectioning (P = .154). Conclusion: Combined ACL-FCL, ACL-PLC, and ACL-PLC-MCL injuries resulted in increasing mean heel-height measurements (2.85, 3.72, and 4.73 cm, respectively) compared to the intact state. Tibial slope was not found to influence increases in heel height. Clinical Relevance: The side-to-side difference in heel height may be a clinically relevant examination tool for diagnosing multiligament knee injuries.

MRI-- and CT--based metrics for the quantification of arthroscopic bone resections in femoroacetabular impingement syndrome.

The purpose of this in vitro study was to quantify the bone resected from the proximal femur during hip arthroscopy using metrics generated from magnetic resonance imaging (MRI) and computed tomography (CT) reconstructed three-dimensional (3D) bone models. Seven cadaveric hemi-pelvises underwent both a 1.5 T MRI and CT scan before and following an arthroscopic proximal femoral osteochondroplasty. The images from MRI and CT were segmented to generate 3D proximal femoral surface models. A validated 3D--3D registration method was used to compare surface--to--surface distances between the 3D models before and following surgery. The new metrics of maximum height, mean height, surface area and volume, were computed to quantify bone resected during osteochondroplasty. Stability of the metrics across imaging modalities was established through paired sample t--tests and bivariate correlation. Bivariate correlation analyses indicated strong correlations between all metrics (r = 0.728--0.878) computed from MRI and CT derived models. There were no differences in the MRI- and CT-based metrics used to quantify bone resected during femoral osteochondroplasty. Preoperative- and postoperative MRI and CT derived 3D bone models can be used to quantify bone resected during femoral osteochondroplasty, without significant differences between the imaging modalities.

Multicenter Outcomes After Primary Hip Arthroscopy: A Comparative Analysis of Two-Year Outcomes After Labral Repair, Segmental Labral Reconstruction, or Circumferential Labral Reconstruction.

PURPOSE: (1) To report minimum 2-year follow-up patient-reported outcome measures in patients undergoing labral repair (LR), segmental labral reconstruction (SLR), or circumferential labral reconstruction (CLR) in the primary setting; and (2) to compare minimum 2-year follow-up patient-reported outcome measures among these groups. METHODS: A retrospective review of a prospectively maintained multicenter database of patients undergoing hip arthroscopy was performed. Inclusion criteria were patients undergoing hip arthroscopy for treatment of labral tear and femoroacetabular impingement syndrome between January 2014 and October 2017, and completion of minimum 2-year postoperative outcome scores. Exclusion criteria were patients undergoing revision hip surgery, labral treatment limited to debridement, lateral center-edge angle <20°, osteoarthritis (Tönnis grade > 1), slipped capital femoral epiphysis, workers compensation status, and patients undergoing concomitant gluteus medius and/or minimus repair. Labral reconstruction patients were matched (1:3) with labral repair patients on age, sex, and body mass index. The labral reconstruction group was further stratified into SLR, and CLR groups. Patient demographic characteristics and clinical outcomes including Hip Outcome Score - Activities of Daily Living, Hip Outcome Score - Sport Subscale, modified Harris Hip Score, international Hip Outcome Tool, and visual analog scale for pain were analyzed, as well as achievement of the minimal clinical improvement difference (MCID). A P-value less than .05 indicated statistical significance. RESULTS: A total of 416 patients were included (LR, n = 312; SLR, n = 53; CLR, n = 51). The age, body mass index, and sex of the matched cohort were 42.3 ± 11.2 years, 24.7 ± 3.7, and 55.0% female. At a minimum of 2-year after hip arthroscopic surgery, no differences were found in preoperative, postoperative, or the delta visual analog scale for pain, modified Harris Hip Score, Hip Outcome Score - Activities of Daily Living, Hip Outcome Score - Sport Subscale, or international Hip Outcome Tool. Subsequently, the proportion of patients achieving the MCID and the PASS at latest follow-up were analyzed. This analysis revealed that no significant differences in the rate of MCID or PASS achievement for any outcome measure existed based on labral treatment. CONCLUSIONS: In this multicenter study on labral treatment in the primary setting, patients undergoing LR, SLR, and CLR demonstrated no difference in preoperative or postoperative scores, nor the proportion of patients achieving clinically significant outcome improvement. LEVEL OF EVIDENCE: III; therapeutic outcome study with controls.

Assessment of Femoral Torsion on Magnetic Resonance Imaging is More Reliable Using Axial-Oblique Sequences Compared With Standard Axial Slices in Patients With Femoroacetabular Impingement Syndrome.

PURPOSE: To determine the agreeability of femoral torsion measurements on axial and oblique axial magnetic resonance imaging (MRI) sequences in patients with femoroacetabular impingement syndrome (FAIS). METHODS: Patients who underwent primary hip arthroscopy for FAIS between January 2012 to January 2019 were identified. Inclusion criteria were all patients with an MRI scan containing the pelvis and knee imaging. MRI-based measurements of femoral torsion were performed on axial and oblique-axial slices by 2 raters, and inter-rater and intrarater reliability was assessed. Bland Altman plots were constructed to evaluate the agreeability between femoral torsion measurements performed using axial and oblique-axial slices. Bivariate correlation analyses were performed to assess the relationship between measurement methods on each respective scan. A linear regression was performed between measurements performed using axial and oblique-axial sequences. RESULTS: A total of 164 patients were included. The mean true-axial and oblique axial femoral torsion were 12.2° ± 9.9° and 11.1° ± 9.2°, respectively. The intrarater reliability for axial and oblique-axial measurements were 0.993 and 0.997, respectively. The inter-rater reliability for axial and oblique-axial measurements were 0.925 and 0.965, respectively. The number of differences within the limits of agreement for axial and oblique-axial femoral torsion measurements was 58.54%. On Pearson correlation analysis, strong positive correlations were found between oblique-axial measurements at multiple time points (r = 0.994, P < .001), as well as axial measurements at multiple time points (r = 0.986, P < .001). A strong positive correlation was found between axial and oblique-axial measurements (r = 0.894, P < .001). A significant regression equation indicated that for each additional increase in axial femoral torsion, the oblique-axial femoral torsion increased 0.837 (95% confidence interval 0.772-0.901). CONCLUSIONS: Femoral torsion values measured on oblique-axial sequences are smaller than on true-axial sequences. Femoral torsion measurements on axial and oblique-axial MRI sequences exhibit poor agreement. Oblique-axial sequences demonstrated greater measurement consistency at multiple timepoints. When evaluating torsional measurements, it is important to delineate which axial sequence was used, especially in patients with suspected severe femoral antetorsion. Standardization of MRI femoral version protocols within one's practice can ensure more consistent decision-making, especially in patients with suspected femoral antetorsion. LEVEL OF EVIDENCE: Retrospective cohort, level III.

Return to Sport in Athletes With Borderline Hip Dysplasia After Hip Arthroscopy for Femoroacetabular Impingement Syndrome.

BACKGROUND: Data on outcomes in patients with borderline hip dysplasia (BHD) who undergo hip arthroscopy remain limited, particularly in regard to return to sport (RTS). PURPOSE: To evaluate outcomes in patients with BHD and their ability to RTS after hip arthroscopy for treatment of femoroacetabular impingement syndrome (FAIS). STUDY DESIGN: Case series; Level of evidence, 4. METHODS: Consecutive patients with self-reported athletic activity and radiographic evidence of BHD, characterized by a lateral femoral center-edge angle (LCEA) between 18° and 25° and a Tönnis angle >10°, who underwent hip arthroscopy for FAIS between November 2014 and March 2017 were identified. Patient characteristics and clinical outcomes including the Hip Outcome Score-Activities of Daily Living (HOS-ADL), Hip Outcome Score-Sports Subscale (HOS-SS), modified Harris Hip Score (mHHS), international Hip Outcome Tool (iHOT-12), and visual analog scale (VAS) for pain and satisfaction were analyzed at minimum 2-year follow-up. In addition, all patients completed an RTS survey. RESULTS: A total of 41 patients with a mean age and body mass index (BMI) of 29.6 ± 13.4 years and 25.3 ± 5.6, respectively, were included. Mean LCEA and Tönnis angle for the study population were 22.7°± 1.8° and 13.3°± 2.9°, respectively. A total of 31 (75.6%) patients were able to RTS after hip arthroscopy at a mean of 8.3 ± 3.2 months. A total of 14 patients (45.2%) were able to RTS at the same level of activity, 16 patients (51.6%) returned to a lower level of activity, and only 1 (3.2%) patient returned to a higher level of activity. Of the 11 high school and collegiate athletes, 10 (90.9%) were able to RTS. All patients demonstrated significant improvements in all patient-reported outcome measures (PROMs) as well as in pain scores at a mean of 26.1 ± 5.4 months after surgery. Patients who were able to RTS had a lower preoperative BMI than patients who did not RTS. Analysis of minimum 2-year PROMs demonstrated better HOS-ADL, HOS-SS, mHHS, iHOT-12, and VAS outcomes for pain in patients able to RTS versus those who did not RTS (P < .05). CONCLUSION: Of the patients with BHD studied here, 75.6% of patients successfully returned to sport at a mean of 8.3 ± 3.2 months after hip arthroscopy for FAIS. Of the patients who successfully returned to sport, 45.2% returned at the same level, and 3.2% returned at a higher activity level.

Sex-Based Differences in Femoroacetabular Impingement Syndrome and the Effect of Cam Deformity Location on the Extent of Labral Tearing: A 3-Dimensional Computed Tomography Study.

Background: Sex-specific quantification of cam morphology in patients with femoroacetabular impingement syndrome may improve diagnostics, surgical planning, and outcomes. Purpose: To (1) examine differences between men and women with symptomatic cam deformities based on deformity location, magnitude, and extent; (2) assess the association between cam deformity and labral pathology; and (3) evaluate the relationship between cam deformity and patient-reported outcome measures after hip arthroscopy. Study Design: Cohort study; Level of evidence, 3. Methods: Computed tomography (CT) scans were acquired in 98 consecutive patients before hip arthroscopy for femoroacetabular impingement syndrome. Custom software was used to generate 3-dimensional bone models and align them to a standard coordinate system. The alpha angle was measured at the 12-, 1-, 2-, and 3-o'clock positions, with 12 and 3 o'clock corresponding to the superior and anterior aspects of the femur, respectively. These alpha angle measurements were used to define the cam midpoint and extent. The labral tear midpoint and extent were evaluated intraoperatively. Bivariate correlation analysis was used to evaluate the association between the cam and labral tear midpoints and between the extent of the cam morphology and labral tearing. Results: The 3-dimensional models were analyzed in a cohort of 69 female and 29 male patients. Male patients were older (mean ± SD, 38.9 ± 12.6 vs 30.7 ± 12.2 years, P = .006) and had a greater body mass index (27.8 ± 4.4 vs 25.3 ± 5.6 kg/m2, P = .005). Male patients had greater alpha angle measures at 12, 1, and 3 o'clock (P < .05) and a greater maximum alpha angle (69.0° ± 18.8° vs 62.1° ± 21.0°, P = .031); the location of their maximum cam impingement was also significantly different (P < .05) when compared with female patients. Cam impingement (2:06 ± 1:09 vs 1:33 ± 1:16 clockfaces, P = .032) and labral tearing (3:02 ± 0:35 vs 2:34 ± 0:53 clockfaces, P = .003) in men extended over a greater region of the femoral clockface when compared with women. Significant correlations were demonstrated between the cam and labral tear midpoint locations (r = 0.190, P = .032) and the extent of the cam deformity and labral tearing (r = 0.203, P = .024). There were no sex-based differences in patient-reported outcome measures at baseline or 2-year follow-up. Conclusion: Male patients possessed greater cam deformity magnitude and extent when compared with female patients. Cam pathomorphology was associated with the location and extent of labral tearing.

Patients Require Less Time to Complete Preoperative Patient-Reported Outcomes Measurement Information System (PROMIS) Than Legacy Patient-Reported Outcome Measures.

PURPOSE: To analyze time to completion of preoperative legacy patient-reported outcomes (PROs) and more recent computer adaptive Patient-Reported Outcomes Measurement Information System (PROMIS) questionnaires in patients with symptomatic femoroacetabular impingement syndrome undergoing primary hip arthroscopy. METHODS: A retrospective analysis was conducted on patients undergoing hip arthroscopy by a single fellowship-trained hip arthroscopist. Inclusion criteria were patients undergoing primary arthroscopic hip surgery and completion of at least 1 legacy PRO or PROMIS questionnaire at the preoperative time point. Exclusion criteria were history of contralateral or ipsilateral hip surgery, non-English-speaking patients, patients who completed PROs by phone or by paper form, and patients who did not complete preoperative PROs. Legacy PROs included modified Harris Hip Score (mHHS), Hip Outcome Score (HOS), International Hip Outcome Tool (iHOT-12), and Hip Pain Visual Analog Scale (VAS-Pain). PROMIS PROs included Physical Function (PROMIS-PF), Pain Interference (PROMIS-PI), and Depression (PROMIS-D). Only preoperative PROs were included in the analysis. Completion time was calculated using the questionnaire start and stop time reported by the survey collecting software. The median and interquartile range of each PRO were reported for analysis of central tendency and statistical dispersion, respectively. RESULTS: A total of 1,901 patients and 269 patients were included in the legacy and PROMIS groups, respectively. The median time required for completion of each PRO in (minutes: seconds) format was as follows: mHHS (1:29), HOS (3:58), iHOT (2:11), VAS-Pain (0:32), PROMIS-PF (0:46), PROMIS-PI (0:37), and PROMIS-D (0:43). The interquartile range of the middle 50% of respondents was as follows; mHHS (0:58), HOS (2:46), iHOT (1:22), VAS-Pain (0:28), PROMIS-PI (0:19), PROMIS-D (0:29), and PROMIS-PF (0:20). CONCLUSIONS: This study supports that preoperative PROMIS forms require less time to complete than preoperative legacy PROs and are not significantly influenced by age, race, or workers compensation status. LEVEL OF EVIDENCE: Level IV, case series.